1. Field of the Invention
This invention relates to telephone receivers; and more particularly to a dual hinged bobbin coil form adapted for mechanical winding of coils thereon for use in telephone receiver assemblies.
2. Description of the Prior Art
Telephone receiver units both currently and in the past have been largely electromagnetic transducers. In most conventional designs dual coils are employed in the electromagnetic structures that form a part of such receivers. Currently such coils are wound on light weight plastic bobbins and present a number of manufacturing problems.
In high volume production manufacturing of such coils it has been desirable to machine wind the wire employed for the coils on plastic bobbins. In the past two separate bobbins requiring a third plastic jig to hold the two bobbins together in an axi-symmetric position for winding have been employed. In this manner a continuous piece of wire is employed for the winding of both coils. This previous arrangement resulted in a high scrap rate due to tangling of wires, broken wires and defective windings. After the jig was removed, which held the coils together during the winding procedure, additional plastic parts were added to facilitate assembly to the receiver unit.
The winding of two coils separately and then joining the wires together and retaining the coils by a common fixture is taught by U.S. Pat. No. 3,243,752. Such an arrangement because of the additional assembly time and winding time involved is not a desirable solution in the telephone receiver coil manufacturing procedure. A solution to the winding of two coils with a single piece of wire is taught in U.S. Pat. No. 3,675,174. However here two separate coils are employed which are then manually joined in an axi-symmetric relationship to permit a single continuous wire to be wound on the first bobbin and then on the second bobbin by mechanical means. Once separated for repositioning in a parallel relationship such as employed in telephone receivers, the fragile wire may be easily broken. In the referenced patent the dual coil unit is incapsulated providing the necessary protection and rigidity, but only after winding is complete. Such an arrangement is not readily adaptable to dual coils as utilized in telephone receivers.
It is the object of the present invention to provide a new and useful dual coil bobbin structure for use with telephone receivers that permits mechanical winding of both coils with a single piece of wire while overcoming the above outlined drawbacks of prior art techniques.